In general, a radiation intensity bolus is a material that is placed in the center of a radiation beam, or placed in contact with or inserted into the body of a patient in order to modulate a radiation dose distribution of radiotherapy.
The radiation intensity bolus is used to increase a tumor radiation dose and to protect surrounding normal tissues by modulating the intensity of radiation in radiotherapy. It is used for electron beam, X-ray, proton, and particle beam radiotherapies. Particularly for the proton and particle beam radiotherapy, the radiation intensity bolus is necessary in order to obtain a radiation dose distribution suitable for the shape of a tumor.
Furthermore, the radiation intensity bolus is used to improve the quality of an image through enhanced beam quality when an image is obtained using radiation since it is effective in adjusting the radiation dose and irradiated region by controlling the intensity of a specific region or blocking the radiation.
Recently, proton and particle beam radiotherapy facilities have become very popular. Since the National Health Insurance has started to cover intensity modulated radiotherapy in Korea, a simple method for intensity modulated radiotherapy is required.
However, conventional intensity modulated radiotherapy uses a radiation collimator for shielding radiation entirely or partially to obtain desired intensity modulated radiation or a bolus made by cutting using milling.
When using a radiation collimator, an error may occur due to the malfunction of the collimator, and it is difficult to calculate a scattered dose occurring in collimator gaps or leaves. It increases the duration of treatment and also increases uncertainty during the radiotherapy of moving organs.
The latter is free from the above disadvantages, but it is difficult to be used in medical facilities due to severe noise from cutting process, generation of contaminated coolant, need for a wide space to accommodate cutting facilities, and the difficulty of high-precision processing.